I. I. Gietlson has written:

'Manmade closed ecological systems'

Because the whole planet is an ecological system,

everything else is just a subsystem.

Amphibians have closed circulatory system Closed

two

An open system in the earth's systems is one in which energy and matter come into the system and also leave the system. An example is any ecological microcosm, where energy, water, and food may be provided or produced. Most could not survive as a closed system, cut off from the Sun and the rain.